Soil–Water Retention Curve Prediction for Compacted London Clay Subjected to Moisture Cycles

Abstract

The evolution of the hydraulic properties of London Clay when compacted at a range of initial conditions (density and water content) was investigated. The soil–water retention curve (SWRC) is observed to change as the soil is subjected to cycles of wetting and drying. A new method is presented for predicting these changes in the soil–water retention curves (SWRCs) based on the starting conditions for each cycle. The method is based on relationships between the degree of saturation before drying (Sr,i), which includes the effect of void ratio and soil fabric, and key parameters that characterize the shape of SWRCs (air-entry value and slope of the transition zone). The relationship between the Sr,i and the air-entry value (or yield point, YP), and the relationship between the YP and the slope of the transition zone of the SWRC were established for the large experimental data set of two types of London clay of high and very high plasticity. The fitting parameters of a bi-linear SWRC model were estimated and used to constrain the fitting parameters of the van Genuchten model. As the SWRC of compacted clay continuously changes with progressive moisture cycles, this model allows the prediction of this evolution for the modelling of earthworks over the years, when subject to changing climatic conditions, without the need for an extensive experimental program.